from __future__ import annotations

from collections import defaultdict
from typing import TypeVar, Generic, Dict, Optional, Iterable, List, Iterator, Tuple, Generator, Union, Any, Set
from .parents import OuterProxy
from ..utils import object_trace
from ..utils import output, BColors

T = TypeVar('T', bound=OuterProxy)


class Collection(Generic[T]):
    __is_collection__ = True

    _data: List[T]

    _indexed_from_id: Dict[int, Dict[str, Any]]
    _indexed_values: Dict[str, Dict[Any, T]]

    shallow_list = property(fget=lambda self: self.data)

    def __init__(
            self,
            data: Optional[Iterable[T]] = None,
            sync_on_append: Dict[str, Collection] = None,
            append_object_to_attribute: Dict[str, T] = None,
            extend_object_to_attribute: Dict[str, Collection] = None,
    ) -> None:
        self._collection_for: dict = dict()

        self._contains_ids = set()
        self._data = []

        # List of collection attributes that should be modified on append
        # Key: collection attribute (str) of appended element
        # Value: main collection to sync to
        self.append_object_to_attribute: Dict[str, T] = append_object_to_attribute or {}
        self.extend_object_to_attribute: Dict[str, Collection[T]] = extend_object_to_attribute or {}
        self.sync_on_append: Dict[str, Collection] = sync_on_append or {}
        self.pull_from: List[Collection] = []
        self.push_to: List[Collection] = []

        # This is to cleanly unmap previously mapped items by their id
        self._indexed_from_id: Dict[int, Dict[str, Any]] = defaultdict(dict)
        # this is to keep track and look up the actual objects
        self._indexed_values: Dict[str, Dict[Any, T]] = defaultdict(dict)

        self.extend(data)

    def __repr__(self) -> str:
        return f"Collection({' | '.join(self._collection_for.values())} {id(self)})"

    def _map_element(self, __object: T, no_unmap: bool = False, **kwargs):
        if not no_unmap:
            self._unmap_element(__object.id)

        self._indexed_from_id[__object.id]["id"] = __object.id
        self._indexed_values["id"][__object.id] = __object

        for name, value in __object.indexing_values:
            if value is None or value == __object._inner._default_values.get(name):
                continue

            self._indexed_values[name][value] = __object
            self._indexed_from_id[__object.id][name] = value

    def _unmap_element(self, __object: Union[T, int]):
        obj_id = __object.id if isinstance(__object, OuterProxy) else __object

        if obj_id not in self._indexed_from_id:
            return

        for name, value in self._indexed_from_id[obj_id].items():
            if value in self._indexed_values[name]:
                del self._indexed_values[name][value]

        del self._indexed_from_id[obj_id]

    def _remap(self):
        # reinitialize the mapping to clean it without time consuming operations
        self._indexed_from_id: Dict[int, Dict[str, Any]] = defaultdict(dict)
        self._indexed_values: Dict[str, Dict[Any, T]] = defaultdict(dict)

        for e in self._data:
            self._map_element(e, no_unmap=True)


    def _find_object(self, __object: T, **kwargs) -> Optional[T]:
        self._remap()

        if __object.id in self._indexed_from_id:
            return self._indexed_values["id"][__object.id]

        for name, value in __object.indexing_values:
            if value in self._indexed_values[name]:
                return self._indexed_values[name][value]

        return None
    
    def _append_new_object(self, other: T, **kwargs):
        """
        This function appends the other object to the current collection.
        This only works if not another object, which represents the same real life object exists in the collection.
        """
        
        self._data.append(other)

        # all of the existing hooks to get the defined datastructure
        for collection_attribute, generator in self.extend_object_to_attribute.items():
            other.__getattribute__(collection_attribute).extend(generator, **kwargs)

        for attribute, new_object in self.append_object_to_attribute.items():
            other.__getattribute__(attribute).append(new_object, **kwargs)

        for attribute, a in self.sync_on_append.items():
            # syncing two collections by reference
            b = other.__getattribute__(attribute)
            if a is b:
                continue

            object_trace(f"Syncing [{a}] = [{b}]")

            b_data = b.data.copy()
            b_collection_for = b._collection_for.copy()

            del b

            for synced_with, key in b_collection_for.items():
                synced_with.__setattr__(key, a)
                a._collection_for[synced_with] = key

            a.extend(b_data, **kwargs)

    def append(self, other: Optional[T], **kwargs):
        """
        If an object, that represents the same entity exists in a relevant collection,
        merge into this object. (and remap)
        Else append to this collection.

        :param other:
        :return:
        """

        if other is None:
            return
        if other.id in self._indexed_from_id:
            return

        object_trace(f"Appending {other.option_string} to {self}")

        
        for c in self.pull_from:
            r = c._find_object(other)
            if r is not None:
                output("found pull from", r, other, self, color=BColors.RED, sep="\t")
                other.merge(r, **kwargs)
                c.remove(r, existing=r, **kwargs)
                break

        existing_object = self._find_object(other)

        # switching collection in the case of push to
        for c in self.push_to:
            r = c._find_object(other)
            if r is not None:
                output("found push to", r, other, self, color=BColors.RED, sep="\t")
                if existing_object is not None:
                    self.remove(existing_object)
                return c.append(other, **kwargs)
        
        if existing_object is None:
            self._append_new_object(other, **kwargs)
        else:
            existing_object.merge(other, **kwargs)

    def remove(self, *other_list: List[T], silent: bool = False, existing: Optional[T] = None, **kwargs):
        for other in other_list:
            existing: Optional[T] = existing or self._indexed_values["id"].get(other.id, None)
            if existing is None:
                if not silent:
                    raise ValueError(f"Object {other} not found in {self}")
                return other

            for collection_attribute, generator in self.extend_object_to_attribute.items():
                other.__getattribute__(collection_attribute).remove(*generator, silent=True, **kwargs)

            for attribute, new_object in self.append_object_to_attribute.items():
                other.__getattribute__(attribute).remove(new_object, silent=True, **kwargs)

            self._data.remove(existing)
            self._unmap_element(existing)

    def contains(self, __object: T) -> bool:
        return self._find_object(__object) is not None

    def extend(self, other_collections: Optional[Generator[T, None, None]], **kwargs):
        if other_collections is None:
            return

        for other_object in other_collections:
            self.append(other_object, **kwargs)

    @property
    def data(self) -> List[T]:
        return list(self.__iter__())

    def __len__(self) -> int:
        return len(self._data)

    @property
    def empty(self) -> bool:
        return self.__len__() <= 0

    def __iter__(self) -> Iterator[T]:
        yield from self._data

    def __merge__(self, other: Collection, **kwargs):
        object_trace(f"merging {str(self)} | {str(other)}")
        self.extend(other, **kwargs)

    def __getitem__(self, item: int):
        return self._data[item]

    def get(self, item: int, default = None):
        if item >= len(self._data):
            return default
        return self._data[item]

    def __eq__(self, other: Collection) -> bool:
        if self.empty and other.empty:
            return True
        
        return self._data == other._data